Processes a container element.
$element: An associative array containing the properties and children of the container.
$form_state: The $form_state array for the form this element belongs to.
The processed element.
function form_process_container($element, &$form_state) {
// Generate the ID of the element if it's not explicitly given.
if (!isset($element['#id'])) {
$element['#id'] = drupal_html_id(implode('-', $element['#parents']) . '-wrapper');
}
return $element;
}